1. Field of Invention
The present invention pertains to the field of control systems. More particularly, this invention relates to network independent transducers for distributed control systems.
2. Art Background
A distributed control system commonly includes a set of transducers and application controllers which are arranged to provide control of industrial and other applications. The transducers that may be employed in a distributed control system include sensors such as temperature sensors, pressure sensors, tachometers, etc. The transducers that may be employed in a distributed control system also include actuators such as valves, motors, heaters etc. Application controllers in a distributed control system may be implemented with programmable logic controllers or computer systems.
The transducers and application controllers of a distributed control system may be interconnected via a communication network. Such a communication network may be implemented with one or more of a variety of differing field-level control buses which are specialized for the process control environment. Such specialized buses may be referred to generally as field-buses. The transducers and application controllers are usually connected as nodes on such a field-bus network.
Typically, existing field-bus networks represent the transducers in a distributed control system using a particular object model. In addition, the object models of transducers usually differ among existing field bus networks. For example, SDS networks have a transducer object model that is incompatible with the transducer object model used in a DeviceNet network.
As a consequence, the manufacturers of transducers must typically provide permutations of their transducers for each of the field bus networks for which they desire to market their products. Typically, each permutation of a transducer is designed and manufactured with the appropriate network interface elements that enable the transducer to be accessed via a particular field bus using the object model appropriate for the particular field-bus. Unfortunately, the permutations of network interface designs for the differing types of field bus networks greatly increases the time and cost required to develop new transducers and increases the cost of supporting the transducers in the field.
A distributed control system is disclosed which includes a network-independent transducer and an electronic data sheet that enables the transducer to be accessed via a variety of differing types of field-bus networks. The electronic data sheet stores a set of object information corresponding to a set of differing object models associated with the differing types of field-bus networks. The distributed control system includes a component node which couples to a particular one of the differing types of field-bus networks and which couples to the transducer through a standard interface. The component node uses the object information to translate between the particular one of the object models and the standard interface during an access of the transducer that originates on the particular one of the differing types of field-bus networks. The electronic data sheet allows the transducer to be employed in a variety of field-bus networks without modifications to existing control system applications.
Other features and advantages of the present invention will be apparent from the detailed description that follows.